Process of concentrating ores



Patented Aug. 8, 1939 UNITED STATES PROCESS OF CONCENTRATING ORES Anderson w. Balaton and William 0. Pool, Chica'go, Ill., asslgnors to Armour. and Company, Chicago, Ill., a corporation of Illinois No Drawing. Application May 23, 1938,

Serial No. 209,604

4 Claims.

This invention relates to flotation agents and processes of concentrating ores therewith, and it comprises as new flotation agents aliphatic secondary amines of the general formula RR'NH.

5 or water soluble salts thereof, where R and R are aliphatic hydrocarbon radicals at least one of which contains from six to eighteen carbon atoms, and it further comprises processes wherein the acid insolubles of ores, such as silica, are

caused to float away from the metal values of the ore by the use of such flotation agents.

Flotation agents are used in great quantities in the concentration of ores by' the flotation methods. The general procedure now employed is to add substances to the aqueous pulp of the ore which so modify the desired values in the ore that these values are floated leaving the gangue behind. This method is the commonly accepted flotation practise either for separating desired values from the gangue or separating one desired value from another- But the purpose of flotation is to effect a separation; if the gangue could be floated away from the desired values the result would be as desirable as the reverse. In other words, the separation could be made as effectively. In fact the froth flotation of the gangue away from the desired mineral values has many advantages. Most of these gangues are siliceous. They are the acid-insoluble portions of the ore, and are, accordingly, insoluble in the common mineral acids. Silica is the chief constituent of the gangue. I

The gangue present in metalliferous and non-- metalliferous ores tends to have more or less the same constitution regardless of the kind of ore.

Thus, in both phosphate ores (wherethe desired values are phosphates) and metalllferous ores (where the desired values are metals) the gangues, or acid insoluble portions, are approxi- 40 mately the same.

The present process, accordingly. relates 'to ways of froth floating the gangue, or acid insolu- ,ble portions of an ore, from the desired mineral values, and we have discovered certain flotation agents useful for this purpose.

We have discovered that secondary aliphatic amines, or the water soluble salts, of the general formula RR'NH where at least one of the R groups contains from six to eighteen carbon atoms, are excellent flotation agents for the separation of acid insoluble gangues from desired values by froth-floating the gangue and thus effecting aseparation. There are many such amines which we can use. Among them are dioctyl amine, dioctyl amine acetate, didodecyl amine, didodecyl amine hydrochloride, dihexyl amine, dihexyl amine acetate, dihexadecyl amine hydrochloride, dioctadecyl amine hydrochloride, butyl dodecyi amine, butyl octadecyl amine hydrochloride, hexyl dodecyl amine acetate, etc.

The following examples illustrate our invention.

Example 1 I A sample of phosphate ore analyzing 21.8% P205, 42.8% acid insoluble, 26.3% aluminum and 3.4% calcium is mixed with water and transferred to a University of Utah flotation cell (capacity 50 grams of ore). Water is then added until the total amount of water is 200 cc. The material is agitated with an electrically driven stirrer (1700 R. P. M.) An amount of dioctyl amine hydrochloride corresponding to 0.3 pound per ton of ore is then added from a medicine dropper, the tip of which has been drawn out to a hair-like capillary. The flotation is then continued for fifteen minutes, -the froth being removed by a Celluloid paddle. This flotation product is collected in a beaker and dried to constant weight in an oven at C. The tailing remaining in the flotation cell is also transferred to a beaker and dried at 130 C. The concentrate and tailing are then weighed separately and a 0.5 gram sample of each analyzed for phosphorus pentoxide, aluminum, calcium and acid insoluble (silica). The following are the results obtained:

I v Insol- Weight P O| ublo Ca Al (silica) Percent Percent Percent Percent Concentrate"... L5 97 0 l 2 0.3

lyzes as follows: P205 33.3%, A1 36.1%, Ca 4.5%,

insoluble (silica) 20.2%. This gives a selectivity index (Ina/P205) of 11.1 and represents a"9l.'7% concentration of the P205 in the timings. When 1.4 pounds per ton of dioctyl amine acetate are used the concentrate weighs 18.6 grams and the tailing 24.8 grams. Analysis of the concentrate is as follows: P10: 1.4%. A1 0.3%. Ca 1.5% and insoluble (silica) 96.6%; and the analysis of the tailing is as follows: P10 37.2%. A1 40.1%, Ca 5.3% and insoluble (silica) 12.4%. This gives a selectivity index (PsOs/IDS.) of 14.4 and corresponds to a concentration of 97.3% of the P20: in the tailings.

Example 2 Dihexyl amine is used with the phosphate ore described under Example 1. 1.4 pounds per ton of dihexyl amine gives a concentration of 91.2% of the Pros in the tailings with a selectivity index of 6.2.

Example 3 Dioctadecyl amine hydrochloride is used with the phosphate .ore described under Example 1. 2.0 pounds per ton gives a concentration of 93.1% of the P30: in the tailings with a selectivity index of 5.1.

Example 4 A sample of ore containing 3.21% copper, 17.8% iron and 41.2% silica is mixed with water and ground in aball mill for fifteen minutes. The pebbles are removed and the water and ground ore transferred to a 2-liter beaker. The slurry is agitated and then allowed to stand for two minutes. The slime is removed by suction. The ground ore is transferred to the flotation cell previously described. Propyl dodecyl amine hydrochloride is added in an amount corresponding to 1.2 pounds per ton of ore and the flotation conducted as under Example 1. The concentrate analyzes 92.6% silica with a silica flotation of 96.3%, thus showing that a separation of silica from the desired metal values has been obtained.

A comparison of the marked effectiveness of the secondary amines with the general ineffectiveness of the primary amines will be of interest to those skilled in the art. For example, when the phosphate ore is floated in the presence of 0.9 pound of dodecyl amine acetate, 9. primary amine, per ton of ore, the concentrate weights 0.5 gram and 53.1 grams remain in the tailing. The concentrate analyzes 53.8% silica and the tailing 38.4% It is evident that this is not a satisfactory separation since the amount floated is negligible. When the amount of dodecyl amine acetate is increased to 6.0 pounds per ton the concentrate weighs 13.3 grams, which analyzes as follows: PzOs 2.7%, A1 0.8%, Ca 1.9% and insoluble (silica) 95.9%; the tailing weighs 40.8 grams and analyses as follows: PaOs 26.6%, Al 30.2%, Ca 4.7% and insoluble (silica) 34.0%. This corresponds to a recovery of 96.8% with a selectivity index of 5.3. It is shown by these results that primary amine salts are in no wise comparable to the salts of secondary amines for this purpose. Dioctyl amine acetate gives a recovery of 97.7% of the silica and a selectivity index of 11.1 when used in a concentration of 0.6 pound per ton, whereas 0.9 pound per ton of dodecyl amine acetate gives no substantial flotation and 6.0 pounds per ton gives a recovery of 96.8% with a selectivity index of only 5.3. The secondary amine produces a tailing containing 33.3% PzOs, whereas the primary amine tailing contains 26.6%. In addition :the separation requires ten times as much primary amine as secondary amine.

Trioctyl amine, a tertiary amine. was investigated and found to give no flotation over wide ranges in ooncentraticn.

For purposes of comparison we also ran flotation experiments with the ore described in Example 1 in the presence of potassium oleate. The behaviour of potassium oleate differs from the secondary amines in that the P205 is concentrated in the froth and the silica is not picked up but is left in the tailings. When we use a concentration of potassium oleate corresponding to 1.5 pounds per ton of ore 24.3 grams floate, which analyze 33.8% P105, 40.7% Al, 5.1% Ca and 11.4% silica; the tailings weigh 28.6 grams and analyze 11.0% PaOa. 13.3% A1, 2.4% Ca and 69.7% insoluble. These results correspond to a phosphate recovery of 72% and a selectivity of 4.3 (PzOs/ Ins.) When the concentration of potassium oleate is increased to 2.8 pounds per ton a concentrate weighing 25.0 grams is obtained and a tailing weighing 25.6' grams. The analysis of the concentrate is as follows: P205 34.6%, A1 41.3%, Ca 5.8% and silica 8.9%; the analysis of the tailing is P20: 9.5%, Al110.6%, Ca 1.9% and silica 75.6%. This corresponds to a recovery of 78% and a selectivity index of 5.6 (Pros/Ins).

From these results it is evident that recoveries when using potassium oleate are not comparable as regards eiilciency or costs to those obtained when using our secondary amines.

The above'data indicate the unusual behaviour of secondary aliphatic amines of the kind stated. Although we have described our flotation process and agents with respect to the separation of phosphate ores, it is understood that our amine flotation agents are equally well adapted for the separation of acid insoluble gangue from other. ores, such as those containing copper, zinc and iron.

Likewise, we can use mixtures of secondary aliphatic amines of the lrincl stated, and salts thereof, and we can add frothing agents, such as cre-, sol, to the flotation agents of the prment invention.

Those skilled in the art will understand that by the language acid insoluble gangue in the appended claims we mean those siliceous materials from which ore values are commonly separated.

Having thus described our invention, what we claim is:

1. In the froth flotation process of separating ore values from acid insoluble gangue, the step including subjecting the ore to froth flotation in the presence of a secondary amine flotation agent chosen from the group consisting of secondary aliphatic amines and water-soluble salts thereof, at least one of the alkyl radicals of such amine or amine salt having from six to eighteen carbon atoms.

2. In the froth flotation process of separating phosphate values from acid-insoluble gangue in phosphate ores, the step including subjecting the ore to froth flotation in the presence of a secondary amine "flotation agent chosen from the group consisting of secondary aliphatic amines and water-soluble salts thereof, at least one of the alkyl radicals of such amine or amine salt having from six to eighteen carbon atoms.

3. The process as in claim 1 wherein the flotation agent is chosen from the group consisting of dioctyl amine and water-soluble salts thereof.

4. The process as in claim 2 wherein the flotation agent is chosen from the group consisting of dioctyl amine and water-soluble salts thereof.

ANDERSON W. RALSTON. WILLIAM O. POOL. 

